Product attribute filters is an indispensible feature of the best shopping carts out there (e.g. Magento), and saves a lot of shoppers' time and frustration from my personal shopping experience. One can see it in action on many of the popular shopping sites such as Best Buy, etc. Product attributes are usually listed in gropus in the very left side bar, i.e. Brand (Samsung, HTC, LG), Color (White, Black), Connectivity (3G, 4G,LTE), etc.